The Gm U1510-00 diagnostic trouble code (DTC) points to a communication issue on the Local Interconnect Network (LIN) bus. This article details the diagnostic process used to pinpoint and resolve a U1510-00 code, alongside a U1501, in a 2017 Chevrolet Silverado LTZ 6.2L. The vehicle presented with an illuminated check engine light (CEL) but ran without noticeable performance issues.
Initial Diagnosis and Research
Initial code scanning revealed both U1501 and U1510 DTCs, indicating a problem with the LIN bus communication within the Powertrain Control Module (PCM). Research revealed a technical service bulletin (TSB) associated with the U1510 code, suggesting a potential ground fault (G102) as a possible cause, often accompanied by intermittent headlight issues. While the customer reported no lighting problems, the G102 ground was inspected. Despite appearing corroded, testing revealed a loaded voltage of approximately 50mV with high beams activated, indicating a functional ground.
Narrowing Down the Culprit
Consulting the vehicle’s wiring diagram, it was determined that the only module connected to the PCM and communicating on the affected LIN bus was the Active Grille Shutter Motor Module. This significantly narrowed down the potential sources of the fault. The diagnostic process then focused on this module.
Examining the LIN Bus Waveform
Accessing the X132 connector for the Active Grille Shutter Motor Module, a lab scope was connected to the GREEN/VIOLET communication wire to analyze the LIN bus waveform. The initial waveform appeared normal at first glance. However, closer inspection revealed that the bus voltage was only being pulled down to around 7 volts, instead of the expected battery voltage (around 12 volts). This deviation suggested a problem within the circuit.
To isolate the issue, connector X132 was disconnected and the waveform was re-examined. With the connector detached, the bus voltage correctly pulled down to battery voltage, confirming that the problem resided within the Active Grille Shutter Motor Module circuit, potentially a faulty module, power or ground issue, or wiring problem between the X132 connector and the module itself.
Final Diagnosis and Repair
Load testing confirmed proper power and ground to the module. This eliminated power and ground issues as the cause. Based on the waveform analysis and subsequent testing, the diagnosis pointed to a faulty Active Grille Shutter Motor Module. Replacing the module resolved the issue and extinguished the CEL. The U1510-00 and U1501 codes did not return after the repair.
